enchanted items can lag the game hard.

how to recreate :

step 1 : 

enchant boots (mine were enchanted with : Soul speed 3, frost walker 2, Protection 4, unbreaking 3, mending 1)

step 2 : 

fill a shulker box with these boots.

step 3 : 

fill a chest with these shulkers.

step 4 : CRTL + middle click  (Copy) the chest and put it in an itemframe, this should make the game lag.